import os
from logging.config import fileConfig

from sqlalchemy import engine_from_config
from sqlalchemy import pool

from alembic import context
from app.db.models import Base

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config

# 从环境变量获取数据库配置
section = config.config_ini_section
config.set_section_option(section, "MYSQL_USER", os.getenv("MYSQL_USER", "root"))
config.set_section_option(section, "MYSQL_PASSWORD", os.getenv("MYSQL_PASSWORD", "admin"))
config.set_section_option(section, "MYSQL_HOST", os.getenv("MYSQL_HOST", "localhost"))
config.set_section_option(section, "MYSQL_DB", os.getenv("MYSQL_DB", "url_shortener"))

# Interpret the config file for Python logging.
# This line sets up loggers basically.
if config.config_file_name is not None:
    fileConfig(config.config_file_name)

# add your model's MetaData object here
# for 'autogenerate' support
target_metadata = Base.metadata

def run_migrations_offline() -> None:
    """Run migrations in 'offline' mode."""
    url = config.get_main_option("sqlalchemy.url")
    context.configure(
        url=url,
        target_metadata=target_metadata,
        literal_binds=True,
        dialect_opts={"paramstyle": "named"},
    )

    with context.begin_transaction():
        context.run_migrations()

def run_migrations_online() -> None:
    """Run migrations in 'online' mode."""
    connectable = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        context.configure(
            connection=connection, target_metadata=target_metadata
        )

        with context.begin_transaction():
            context.run_migrations()

if context.is_offline_mode():
    run_migrations_offline()
else:
    run_migrations_online() 